Marquez Callaway

So what happened on that OPI that wiped out Callaway's TD? It looked to me like TQS was just running his route -- I didn't see a pick. Am I wrong?
It was an iffy call at best, but I can see why it was called if the ref wasn't looking directly at them when it happened. Sucks for Callaway, who should have had two TDs and over 100yds if not for circumstances that were out of his control.